High temperature shaft or roll



Mai-ch 28, 1939. P. s. MENOUGH HIGH TEMPERATURE S HAFT 0R ROLL FiledJuly 15, 1936 Patented Mar. 28, 1939 PATENT orFicE "HIGH TEMPERATURESHAFT R ROLL I a Paul S. Menough, Pittsburgh, Pa., assignor to MichianaProducts Corporation, Michigan City, Ind., a corporation of IndianaApplication July 15, 1936, Serial No. 90,754 I 6 Claims.

, Thisinvention relates-to shafts or rolls for use under hightemperature conditions and more particularly for use in high temperaturefurnaces. I One of the objectsof the invention is the provision of a newand improved high temperature shaft or roll that is formed from sectionsprovided with novel means for connecting the sections together.

Another object of the invention is the provision of a new and improvedfurnace shaft having a cast central portion and having end portionswelded thereto by a weld that is so arranged that only portions of theweld extend in the direction of rotation of the shaft or roll wherebythe parts willbe more nearly permanently connected together.

A still further object of the invention is the provision of a new andimproved furnace shaft having a centrifugally cast central portion,provided with reduced end portions attached theretg by welds arranged atan angle to the direction; of travel of the shaft whereby the welds willmore firmly hold the parts together and reinforce the carrying capacityof the shaft. A further'object of the invention is the provision of anew and improved sectional furnace shaft having novel means forconnecting the sections together, that is inexpensive to manufacture,strong, rugged, emcient in use, and. that is not likely to become bent,distorted, broken, or the parts become disconnected. while in operation.

Other and further objects and advantages of the invention, will appearfrom the following description taken in connection with the accompanyingdrawing, in which Fig. 1 is a vertical section of a furnace, shown indotted lines, showing the invention in position therein, with parts in'section and parts broken Fig. 2 is a section on the line 2 -2 of Fig. 1

Fig. 3 is a front elevation of a modified form of the shaft, with partsin section and parts broken away;

Fig. 4 is an elevation of one end of the central section of the shaft ofFig.3 before the assembled;

Fig. 5 is an, end elevation thereof Fig. 6 is an elevation of an endportion of a modified form of shaft, with parts broken away 50 and partsin section; 1 v

Fig. 'lis a vertical section of the end section of the shaft shown inFig. 6, with parts broken away;

- Fig. 8 is an elevation of the central portion of tlieshaft'showninFig. 6, with parts broken away;

55 and shaft is (cl. ass-cl Fig. 9 is an elevation of a carbonizingretort, with parts in section and parts-broken-away.

It is common practice to employ a plurality of rotating shafts whichform conveyors for transferring material through the furnace while the 5same is being heat treated.

More or lessdifficulty has been experienced in .the use of these shaftsdue to the intense heat to which they aresubjected in certain types offur-. naces. The qualifications for; the shafts are 10 rather exacting.They must have sufflcient strength under high temperatures so that theywill not bend, break or become distorted while in use. They mustbesymmetrical, strong and durable, and free from defects in theirconstruction. 15

The present invention has for its principal object, the provision ofshafts of superior quality.

' This is accomplished by centrifugally casting the central portion ofthe same from heat resisting alloys, and by securing the end portions tothe 20 central portion in a novel manner.

These shafts have been made by casting metal in conventional stationarymolds. Numerous weaknesses have developed in'castings so made. It isvery difllcult to hold a heavy core in the center of the mold whilemolten steel is being poured around it. If the core does not remain inthe center of the mold,tlie walls of the casting willnot be uniform inthickness. This means that the metal in the walls will freeze orsolidify at 80 different rates,- As molten metal solidifies, it

; shrinks. Consequently, the lighter sections of the wall, as theyfreeze first, will draw molten metal from the heavier sections tocompensate for this liquid shrinkage. This will cause shrinkage voids.

or at least'porosity to be formed in the heavier wall sectionswhichfreeze last. Also, the low melting segregates will migrate to theportion of the casting which is the last to freeze and there will bepresent in these heavy. sections not only 40 shrinkage cavities, butalso, in the same locality, a concentration of segregates. Moreoverthese shrinkage voids and their accompanying segreations will be buriedin the middle of the wall and cannot be detected by any surfaceinspection.

side. This will cause the casting to warp.

exaggerated in chromenickel steel castings are automatically correctedby making such castings centrifugally. The wall thickness is determinedby centrifugal force and is uniform in all portions of a centrifugalcasting. This means there will be no heavy sections, the casting willfreeze uniformly and there=will be no shrinkage, no concentration ofsegregation s, and no warpage.

The present invention seeks to remedy these difficulties by theprovision of shafts made in sections, the central or principal sectionbeing centrifugally cast, and the end section or sections being rigidlyconnected thereto by welding or the like. This central section, beingcentrifugally cast. will be symmetrical about its longitudinal axis; thebest of the material will be on the 'sur- 1 face thereby addingmaterially to the strength and heat resisting property of the shaft;there will be no blow holes or defective parts in the surface of therolls; the dross and lighter material will be on the inner surface; andthe entire material. will be equally distributed about the axis of theshaft.

I have found that shafts made from heat resisting alloy, such asiron-chromium-nickel, give the best results when centrifugally cast, butdue to the fact that the openings in the furnace walls through which theends of the shafts extend, must be limited in area in order to preventthe escape of the furnace heat therethrough, it is common practice toreduce the ends of the shafts to extend through these openings- Sincethese shafts are tapered at the ends and the walls of the centralportion are of such thickness that the axial opening is not of uniformdiameter throughout the length of the'shaft, the

- means including welding. In order that thesethe separately east endportion are joined onlyv shaft, when centrifugally cast, must be made insections. They are preferably made in three sections, the centralportion only is centrifugally cast and the end sections are connectedthereto by welds may resist both the torque of the operating mechanismand also support the load of the material that is being treated, theweld or welds are so arranged that they extend not onlycircumferentially around the shaft but also at an angle or angles to thedirection of rotation.

This is considered an important feature of the invention. If thecentrifugally cast barrel and by a circumferential weld, the bendingmovement of the shaft has a tendency to become a maximum on the weld.The reason for this is that when a single circumferential weld isemployed one section is telescoped within the other and since anylooseness whatever in the; joint will tend to permit the shaft to bendslightly at'l-C the joint, such bending will, of course, tend to disruptthe weld. It will be noted that such a butt weld, when it is at the topof the shaft will be in compression. A half revolution later when it '22,1t2,o7e'

rates, the thin side will shrink ahead of the thick imposed load. If theend sections are telescoped within the ends' of the central bodysection, it

would appear at first glance, that the same result as outlined abovewould be achieved, namely: a leverage which would act against thebending {load of the shaft. This, howeveizis not true. All the heatwhich reacts on the male'portion of this joint must come through thecentral shaft which encloses it. The heat conductivity of chromiumnickel steel is very poor. Consequently, the end of the central or bodysection will get hotter than the inserted end of the end the bendingload to be concentrated in a weaving stress on the weld itself;

This means that by extending these welds not only circumferentially, butalso longitudinally, it

has been found that this weaving stress is effectually resisted.

Referring now to the drawing, the reference character 8 designates afurnace having the walls ii and i2 shown in dotted lines. These wallsare provided with openings l3 and I4 through which the reduced ends l5and I6 of a furnace shaft I! extend, as is usual in such constructions.A sprocket or the like 20 -on thereduced portions of the shaft isprovided for operating the shaft in the usual manner.

It is common practice in heat treating furnaces to provide a pluralityof parallel shafts or rolls extending transversely across the furnaceand rotating the same by suitable mechanism to form a conveyor fortransferring material that-is being treated through the furnace. Sincethe details of the furnace constitute no part of the present invention,it is not thought necessary to further illustrate .or describe the same.

. section and will. expand away from it, allowing Each of the shafts l1comprises a central secchromium together shall be not less than and notmore than 60%. This alloy is preferably centrifugally cast to-form theblank for the central section i8 of the shaft. The central sect on blankis cylindrical and may, if desired, be cast with ribs 22 thereon forsplining material transporting disks to the shaft as is usual n suchconstructions. These ribs will materially reinforce the shaft.

By centrifugally casting the alloy, the heavier and consequently thetougherand stronger portions of'the alloy will be at the outer surfaceof the shaft or roll thereby adding materially to the strength of theshaft or roll in resisting bending or distortion thereof. By casting theribs -22 on the surface of the shaft or roll the thickness of the metalof the shaft maybe reduced since the ribs will contain thebest andstrongest portions of the metal, thereby adding materially to theresistance to bending ofthe shaft or roll. .7 i

The end sections 89 and 2| of the shaft or roll have reduced portions 15and I6, each of which terminates at its inner end in a flared portion 23which merges into a cylindrical portion 261 which is of such diameterthat it may beinserted in one end of the central section I8. The

end sections after they have been inserted in the ends of the tubularcentral section, I, are secured in position by welding. The parts are soarranged that at least some of the welds extend in a direction at anangle to the direction of rotation of the shafts. This may beaccomplished in any suitable manner.

In the form of the construction selected to illustrate one embodiment ofthe invention, which is by way of example only, the ends of the centralsection l8 are provided with slots 25 extending longitudinally of thesection. These slots are of' any appropriate length, but, of course. donot extend inwardly beyond the inner ends of the cylindrical portion 24of the end section. Any suitable number of these slots may be provided,two being shown for each end.

latter as thecentral section expands thereby' more or less relieving thewelds from the stresses caused by this differential radial expansion.

After the parts are assembled, welds 27 and 28 are applied around theedges of thecentral section 3 and around the edges of the slots 25,respectively.

It will thus be seen that the welds 27 and 28 willnot only resist thetorque of the operating mechanism, but the welds 28, which extendlongitudinally of the central portion will resist any bending or radialmovement of the end sections relative to the central section. Thesewelds, in other words, will hold the end and central sections fromrelative rotation and will also retain them in co-axial relation.

The form of the construction shown in Fig. 3 differs from that justdescribed in that the end sections 29 of the shaft 3| are of a slightlydifferent construction from the corresponding ends l9 and 2| describedabove and the end portions of the middle section 52 are formeddifferently and are attached in a different manner. In this form ofconstruction,.the central section 32 is preferably, though notnecessarily,

centrifugally cast and its ends are of such a contour that the welds,for the mostpart, will extend at an angle to the direction in which theshaft is rotated.

In the form of the construction shown, the ends of the central portion32 are scalloped, that is, triangular sections are, removed to form V-shaped'rece'sses 33 and tapered portions 50 ex-' tending about the endsof the section so that the edges at the end of the section will form amore or less zig-zag line around the section.

Each of the end sections 29 is provided with In fabricating the device,the end sections are inserted in the ends of the central section 32, andthe tapered portions 30 bent down onto the flared portions 35. Theirlength is'such' as to leave a recess 39 between their ends and theenlarged portion 38. The recess 39'and the space .between the taperedportions ill may then be lined with welding material as shown at theleft in Fig. 3.

In the modified form of the construction shown 'in Figs. 6, '7 and 8,the ends and central portions are so constructed that there is aninterlocking connection between the same. By means of this arrangement,the welds are relieved of the torque action of the rotating mechanism.Such an arrangement is desirable for use in furnaces which require ahigh starting torque on the shafts.

In this form of construction, each end of the central section 4| may beprovided with a plurality of projections or tongues 42 which may bespaced from each other a suitable distance as may be desired. Theseprojections or tongues may be of any suitable shape. In the form shown,they are tapered outwardly and are adapted to engage. in correspondingtapered recesses #33 formed in the flared portions M of the end sectionsd of the furnace shaft 55. The end sections 435 may be, and preferablyare, provided with integral'cylindrical portions 239 for telescoping theends of the central or body portion ii and with radial flanges dB forlimiting the lateral movement of the material as it passes through thefurnace. The horizontal web 49 is provided with a plurality of openings5i for receiving the weld as will presently appear.

When the parts are assembled, the projections or tongues on the flaredportion M1 and on the central section M engage in the correspondingrecesses, the projections or tongues 42 being bent inwardly to engage inthe recesses 43. The parts are so constructed and arranged that theprojections or tongues 42 are flush with the flared walls 4.4 and themeeting line of the parts constitutes a more or less zig-zag line aroundthe end of the shaft.

It will be noted that in this form of the construction, the parts of theshaft that abut are telescoped as in the previous constructions but theend sections are on the outside. The parts are held in position by welds52 and 53 which extend along the abutting line of the two sections andin the recesses 5!, respectively.

In Fig.,9 is shown a.further modified form of construction. This form ofconstruction is shown as applied to a retort which is adapted to be usedfor carbonizing and the like. Inthis form ofthe construction, the retortis in two sections, a body 54 and an end section 55. The end section 55has one end 56 of substantially the same diameter as the body portion 54and is provided with outwardly extending tongues 51 which may havetapered sides, as shown at 58, for engaging in correspondingly shapedrecesses, or complementary recesses 59 formed in the line formed by thetongue and the recesses.

It will thus be seen that in all forms of construction there are certainor the welds that extend in a direction at an angle to the directionof'rotation of the shaft, that is, there are welded portions spacedlongitudinally of the shaft or roll. 'Just what form or shape theweld-may have is immaterial so long as certain portions of it or certainwelds extend at an angle to the direction of rotation or are spacedlongitudinally of the shaft or roll, is all that is necessary.

The open end of the retort is adapted to extendthrougha correspondingopening in the furnace wall as is usual in such constructions. This endof the retort is provided with thickened portion forming a flange orring to which the cover may be attached.

While I have disclosed the invention in the form'of shafts or rolls foruse in heat treating furnaces, it is understood that rolls foruse inrolling mills for rolling -metal bars, sheets,

commercial iron, or rolls for use in manufacturing plate glass and thelike, may be made by centrifugally casting the same, or at least thecentral sections thereof, and have the end sections comprising thejournals attached by setrated welds or welds having portions arrangedlongitudinally of the shaft or roll, as indicated changes in size,shape, proportion and details of construction may be made withoutdeparting from the spirit'and scope of the appended claims.

I claim as my invention: 1. A conveyor shaft for heat treating fur nacescomprising a central section centrifugally cast of high heat resistingmaterial and end sections provided with reduced ends forming journalsfor said shaft; the end sections lapping the central sections and atleast a part 7 of the lapping portion being telescopic, one of thelapped portions at each end of the shaft having open end recessestherein extending longitudinally of the shaft, and a weld extendingalong said recesses for connecting said sections together, said weldhaving portions thereof extending longitudinally of the shaft and otherportions extending around said shaft in a circumferential direction.

2. A sectional tubular shaft for use in heat treating plants comprisinga central section of heat resisting alloy, end sections each havingportions telescoping the adjacent end of the central section and havinga reduced portion constituting a journal for said shaft, and weldsconnecting said central and end portions together, said welds havingportions extending longitudinally and other portions extendingcircumferentially of the shaft rigidly securing eachv end section to thecentral section.

3. A rotatable roll comprising a sectional tubular conveyor shaft ofhigh heat resisting al loy having reduced end portions forming journalsfor said shaft, the central portion of said shaft being centrifugallycast from a heat resisting alloy, said sections having telescopingportions having interlocking projections on their adjacent endsconnected together by welds, certain of which extend circumferentiallyof the shaft and others in a-direction longitudinally 10 of the shaft,the interlocking portions of said sections being flush on their outersurfaces.

4. A sectional tubular shaft for use inheat' treating. furnacescomprising a central section cast from a heat resisting alloy, endsections 15 each having a tapered portion merging into a including endsections anda central section of 30,

high heat resisting material, each end section having its outer endreduced and coaxial with the central section to. form Journals for saidroll and its inner end, portion flared, the ends of said central sectionbeing complementally tapered and slotted to provide tongues, saidtongues lapping the flared portion of the adjacent end section, andwelds extending along the marginal edges of said tongues and securingsaid sections together.

6. A conveyor shaft for heat treating furnaces comprising a centralsection of high heat resisting material and end sections provided withreduced ends forming journals for said shaft, the end sections lappingthe central section at each end of the central section-and at least apart of the lapping portions being telescopic, the portions of saidshaft sections that are telescoped being welded together at intervalsabout their circumference at the inner and outer marginal portion of azone the width of which is substantially the same as the length of thelapping. portions.

PAUL S. MENOUGH.

